electricus
Member
- Location
- wisconsin
Want to know what is suggested for a work shop.
What is the amount of watts/square foot suggested for lighting applications?
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electricus
Member
- Location
- wisconsin
After reading that article, they guy that wrote it makes it sound like all other articles dance around the point, but he is not going to. Well he does, he uses a lot of big words, and in the end basically says that once everything is set up then take a foot candle reading and make adjustments. What I got out of it is that lighting is an experiment. I get that, but I wanted to try to get it right the first time during the rough in stage and not have to make difficult changes once everything is finished. Let the experimenting begin.
BullsnPyrs
Senior Member
- Location
- Saint Joe, Arkansas
Cooper lighting has a calculator you can use for photometrics.
http://www.cooperindustries.com/content/public/en/lighting/resources/design_center_tools/photometric_tool_box.html
Use the calculator to lay out your room.
http://www.cooperindustries.com/content/public/en/lighting/resources/design_center_tools/photometric_tool_box.html
Use the calculator to lay out your room.
electricus
Member
- Location
- wisconsin
Got it downloaded, but not user friendly to the layman, and unless one is using Cooper products, or know which model is closest to what you have, this is a tough on to use. Did some more research and came up with the general consensus that most people out there have 2 to 2.5 watts per square foot, or 80 - 100 fc. One would need a foot candle meter and this all testing after the fact, the height of the meter off the floor also makes a difference.
One thing I did not consider off the bat is that nothing is 100% efficient. The original amount of florescent strip fixtures I was going was not enough. I figured more the get me to 2.5 watts/sq. ft., but then realized if they only output light at around 90% once used for a while I would need to add another fixture or two just to make up for the inefficiency. Hope that part helps for who ever is trying to figure lighting on there project.
I think I have it figured out and have a plan I'm going to go with.
One thing I did not consider off the bat is that nothing is 100% efficient. The original amount of florescent strip fixtures I was going was not enough. I figured more the get me to 2.5 watts/sq. ft., but then realized if they only output light at around 90% once used for a while I would need to add another fixture or two just to make up for the inefficiency. Hope that part helps for who ever is trying to figure lighting on there project.
I think I have it figured out and have a plan I'm going to go with.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
I gotta try that idea of using a smart phone as a light meter. Cool.:thumbsup:
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
The Cooper link is, as you say, for their products.
BUT ... the issue really is that different lighting systems have widely different efficacy values measured in lumens per watt. Just for grins, look at http://en.wikipedia.org/wiki/Luminous_efficacy. You'll see lumen/watt values in the 15/20 range for incandescent, 60-100 range for fluorescent, and 80-200 range for the various gas discharge products.
This is at least a 5:1 range in how much light you get from each watt of electricity ... thus the reason a watt/area for LIGHTING is not much used anymore.
Reflectivity of the walls, ceilings, and floors ... and to the cabinets and other finishes ... come heavily into play, too.
If you use good fluorescent fixtures, ballasts, and lamps (tubes?) or one of the gas discharge technologies, highly reflective walls and ceiling, I SUSPECT that 1 watt/ft^2 will be PLENTY. If you use absorptive finishes, multiple low power incandescent lamps with inefficient covers, I DOUBT that 10 watt/ft^2 will be enough. It MAY be important to consider light color as well.
For workshop, medium type of detail, IES recommendations are 500lx (or approx 50fc). The range of 80-100fc seems a bit excessive to me but of course much depends on the type of work done in that shop. Note that this is average level, not peak. Also, your ceiling height and luminare mounting height are important parts of the equation.
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kwired
Electron manager
- Location
- NE Nebraska
Watts will be completely different for incandescant lighting than it is for T8 or T5, or even HID.
I think you want to ask how much light is suggested and figure watts needed based on type of light to be used.
BullsnPyrs
Senior Member
- Location
- Saint Joe, Arkansas
If you are using strip fixtures there is not a l;ot of difference between cooper's fixtures and any other manufacurers unless you get into fixtures with reflectors which increase the efficacy of the fixture. Set your cieling hieght as the distance from your work surface to the cieling to design for light levels on your work surface.
Watts/sq ft are only used in energy codes to limit power consumption and for retrofit tax credits from the feds. When designing for light levels use Foot Candles.
kwired
Electron manager
- Location
- NE Nebraska
OP needs to clarify if he is wanting to know how much light is recommended or if his concern was how much load to account for, or both. Style of light is typically needed first to know how to proceed with the other calculations.
maghazadeh
Senior Member
- Location
- Campbell CA
One fixture with 3 - T8 lamps per 80 sq ft. should give you approx 50 - 55 fc on work surface about 30" from floor when installed about 8 - 9 ft from floor. lighter paint on ceiling, walls, and floor will increase the fc.
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